Quantum Communication Protocols Research Articles

Hybrid bidirectional quantum communication with different levels of control with simulation

In this paper, we develop a quantum communication protocol for the simultaneous preparation of a two-qubit and a three-qubit state at the positions of two different parties situated spatially apart. For one party, Alice, it is a remote state preparation of a known two-qubit state while for the other party, Bob, it is a joint remote state preparation with the help of a third party, Eve. The protocol is executed in a hybrid form bi-directionally in the presence of two controllers, Charlie and David. There is a hierarchy in the process through different levels of control under which the actions by Alice and Bob are performed. There is a need for a ten-qubit entangled channel connecting the five parties. The generation of this channel through a circuit is discussed. The protocol is executed on the IBM Quantum platform. We also study the effect of noise on our protocol. Here, amplitude-damping, bit-flip and phase-flip noisy environments are considered and the corresponding variations of fidelity are theoretically and numerically analyzed.

Hybrid quantum communication protocol for fiber and atmosphere channel

Hybrid quantum communication protocol for fiber and atmosphere channel

Single and entangled photon pair generation using atomic vapors for quantum communication applications

Significant progress has been achieved in leveraging atomic systems for the effective operation of quantum networks, which are essential for secure and long-distance quantum communication protocols. The key elements of such networks are quantum nodes that can store or generate both single and entangled photon pairs. The primary mechanisms leading to the production of single and entangled photon pairs revolve around established techniques such as parametric down-conversion, four-wave mixing, and stimulated Raman scattering. In contrast to solid-state platforms, atomic platforms offer a more controlled approach to the generation of single and entangled photon pairs, owing to the progress made in atom manipulation techniques such as trapping, cooling, and precise excitation schemes facilitated by the use of lasers. This review article delves into the techniques implemented for generating single and entangled photon pairs in atomic platforms, starting with a detailed discussion of the fundamental concepts associated with single and entangled photons and their characterization techniques. The aim is to evaluate the strengths and limitations of these methodologies and offer insights into potential applications. Additionally, the article will review the extent to which these atomic-based systems have been integrated into operational quantum communication networks.

Joint encryption and error correction for secure quantum communication

Secure quantum networks are a bedrock requirement for developing a future quantum internet. However, quantum channels are susceptible to channel noise that introduce errors in the transmitted data. The traditional approach to providing error correction typically encapsulates the message in an error correction code after encryption. Such separate processes incur overhead that must be avoided when possible. We, consequently, provide a single integrated process that allows for encryption as well as error correction. This is a first attempt to do so for secure quantum communication and combines the Calderbank-Shor-Steane (CSS) code with the three-stage secure quantum communication protocol. Lastly, it allows for arbitrary qubits to be transmitted from sender to receiver making the proposed protocol general purpose.

N-qubit universal quantum logic with a photonic qudit and O(N) linear optics elements

High-dimensional quantum units of information, or qudits, can carry more than one quantum bit of information in a single degree of freedom and can, therefore, be used to boost the performance of quantum communication and quantum computation protocols. A photon in a superposition of 2N time bins—a time-bin qudit—contains as much information as N qubits. Here, we show that N-qubit states encoded in a single time-bin qudit can be arbitrarily and deterministically generated, manipulated, and measured using a number of linear optics elements that scale linearly with N, as opposed to prior proposals of single-qudit implementation of N-qubit logic, which typically requires O(2N) elements. The simple and cost-effective implementation we propose can be used as a small-scale quantum processor. We then demonstrate a path toward scalability by interfacing distinct qudit processors to a matter qubit (atom or quantum dot spin) in an optical resonator. Such a cavity quantum electrodynamics system allows for more advanced functionalities, such as single-qubit nondemolition measurement and two-qubit gates between distinct qudits. It could also enable quantum interfaces with other matter quantum nodes in the context of quantum networks and distributed quantum computing.

Hiding Images in Quantum Correlations.

Photon-pair correlations in spontaneous parametric down-conversion are ubiquitous in quantum photonics. The ability to engineer their properties for optimizing a specific task is essential, but often challenging in practice. We demonstrate the shaping of spatial correlations between entangled photons in the form of arbitrary amplitude and phase objects. By doing this, we encode image information within the pair correlations, making it undetectable by conventional intensity measurements. It enables the transmission of complex, high-dimensional information using quantum correlations of photons, which can be useful for developing quantum communication and imaging protocols.

Hybrid multi-directional quantum communication protocol

Hybrid multi-directional quantum communication protocol

(Invited) Next-Generation Photonic Source Based on Lateral GaAs/AlgaAs Heterostructure Devices

Quantum communications and remote sensing protocols rely on preparing individual quanta of light, or photons, as carriers of quantum information. While it is easy to generate many-photon classical states of light (e.g., a light bulb or a laser), it is challenging to generate single quanta or pairs of entangled quanta on-demand. Yet, only in this latter regime can the fundamentally quantum nature of light be exploited to achieve performance exceeding classical bounds.We are developing a single-photon source based on combining a one-parameter single electron pump (Figure 1a,b) – an electrically controlled, on-demand, high-fidelity emitter of single electrons [1] – with a lateral p-n junction [2] (Figure 1c,d) in which injected single electrons recombine with holes to produce single photons. These devices are realized in undoped GaAs/AlGaAs heterostructures and designed to be ambipolar. Such a quantum light source could lead to a paradigm shift in metrology, providing a quantum redefinition of two of the seven SI base units, the ampere and the candela. It is also possible in principle to realize scalable source arrays on a single chip. I will discuss progress towards realizing and characterizing these sources, including work on optimizing collection efficiency and Purcell enhancement using a lateral distributed Bragg reflector in a concentric ring geometry. Beyond fundamental studies, the proposed photon source will find practical use in quantum communications protocols (QKD), where it can offer fast data transmission rates, and quantum sensing with LiDAR, where it could outperform laser-based systems in the few-photon regime for low-power, stealth applications.[1] B. Buonacorsi et al, “Non-adiabatic single-electron pumps in a dopant-free GaAs/AlGaAs 2DEG”, Appl. Phys. Lett. 119, 114001 (2021).[2] L. Tian et al, “Stable electroluminescence in ambipolar dopant-free lateral p-n junctions”, Appl. Phys. Lett. 123, 061102 (2023). Figure 1

A High-Reliability Quantum Communication Protocol via Controllable-Signal Attenuation

Since the protocol for counterfactual quantum communication was proposed, complete counterfactuality can be achieved as there are no physical particles in the transmission channel. However, it relies on some restrictive factors, such as requiring an infinite number of beam splitters and no degradation. We conducted numerical simulations to assess the reliability of quantum communication combined with the actual test environment and found that the inevitable degradation, including component losses or path losses, limits the number of beam splitters. Furthermore, we carried out the experimental simulation of a high-reliability direct communication protocol using the method of controllable-signal attenuation. The peak reliability of μ1=27.6±0.22 that was obtained was much higher than the current communication protocol of the chained interferometer system. The optimized experimental equipment could compensate the system’s balance under various restrictive conditions and make it possible to achieve 100% reliability with imperfect interferometers.

Optical payload design for downlink quantum key distribution and keyless communication using CubeSats

Quantum key distribution is costly and, at the moment, offers low performance in space applications. Other more recent protocols could offer a potential practical solution to this problem. In this work, a preliminary optical payload design using commercial off-the-shelf elements for a quantum communication downlink in a 3U CubeSat is proposed. It is shown that this quantum state emitter allows the establishment of two types of quantum communication between the satellite and the ground station: quantum key distribution and quantum keyless private communication. Numerical simulations are provided that show the feasibility of the scheme for both protocols as well as their performance. For the simplified BB84, a maximum secret key rate of about 80 kHz and minimum QBER of slightly more than 0.07% is found, at the zenith, while for quantum private keyless communication, a 700 MHz private rate is achieved. This design serves as a platform for the implementation of novel quantum communication protocols that can improve the performance of quantum communications in space.

Quantum broadcasting of the generalized GHZ state: quantum noise analysis using quantum state tomography via IBMQ simulation

This study focuses on the challenges posed by quantum noise to communication protocols, with a particular emphasis on the vulnerabilities of current quantum broadcast protocols. The research employs the generalized GHZ state, known for its multipartite entangled cluster state with real-value coefficients, as a diagnostic tool to understand and address the impact of quantum noise on transmitted information. Implementing two novel controlled quantum broadcast schemes on the IBM Quantum (IBMQ) Experience platform, using the Qiskit library and the QASM simulator, the investigation evaluates the effects of four different types of quantum noise through Kraus operator models. A notable aspect of the study is the pioneering use of quantum state tomography for a comprehensive analysis of quantum noise effects, providing novel insights into the resilience of quantum communication protocols.

Good Gottesman-Kitaev-Preskill codes from the NTRU cryptosystem

We introduce a new class of random Gottesman-Kitaev-Preskill (GKP) codes derived from the cryptanalysis of the so-called NTRU cryptosystem. The derived codes are good in that they exhibit constant rate and average distance scaling Δ∝n with high probability, where n is the number of bosonic modes, which is a distance scaling equivalent to that of a GKP code obtained by concatenating single mode GKP codes into a qubit-quantum error correcting code with linear distance. The derived class of NTRU-GKP codes has the additional property that decoding for a stochastic displacement noise model is equivalent to decrypting the NTRU cryptosystem, such that every random instance of the code naturally comes with an efficient decoder. This construction highlights how the GKP code bridges aspects of classical error correction, quantum error correction as well as post-quantum cryptography. We underscore this connection by discussing the computational hardness of decoding GKP codes and propose, as a new application, a simple public key quantum communication protocol with security inherited from the NTRU cryptosystem.

Controlled remote implementation of operations for many systems

Quantum communication plays a key role in the next generation of information transfer and security schemes, by using quantum entanglement and measurements from quantum mechanics. We introduce the mathematical and physical foundations of quantum communication, such as the CNOT gate and Kronecker product. Then we propose two quantum communication protocols, namely dense coding and stealth coding. These protocols offer unique advantages that are theoretically unbreakable. Then we extend the protocols to the quantum communication protocol allowing for third-party supervision to ensure information security. Based on this, a communication protocol involving four parties is designed, enabling them to exchange information while being supervised.

Complete analysis of hyperentangled Bell state in three degrees of freedom using Kerr effect and self-assisted mechanism

We present an efficient scheme for the complete hyperentangled Bell state analysis (HBSA) of photon system with polarization and two longitudinal momentum degrees of freedom (DOFs), resorting to weak cross-Kerr nonlinearity, linear optical elements and single photon detectors. In the process of distinguishing the 64 hyperentangled Bell states in three DOFs, the self-assisted mechanism is embedded, which makes our scheme simple and realizable. Moreover, we have discussed the applications of this complete HBSA scheme for high-capacity quantum communication protocols that are based on photonic hyperentanglement in three DOFs.

Increasing quantum communication rates using hyperentangled photonic states

Quantum communication is based on the generation of quantum states and exploitation of quantum resources for communication protocols. Currently, photons are considered as the optimal carriers of information, because they enable long-distance transition with resilience to decoherence and they are relatively easy to create and detect. Entanglement is a fundamental resource for quantum communication and information processing, and it is of particular importance for quantum repeaters. Hyperentanglement, a state where parties are entangled with two or more degrees of freedom (DoFs) simultaneously, provides an important additional resource because it increases data rates and enhances error resilience. However, in photonics, the channel capacity, i.e., the ultimate throughput, is fundamentally limited when dealing with linear elements. We propose a technique for achieving higher transmission rates for quantum communication by using hyperentangled states, based on multiplexing multiple DoFs on a single photon, transmitting the photon, and eventually demultiplexing the DoFs to different photons at the destination, using Bell state measurements. Following our scheme, one can generate two entangled qubit pairs by sending only a single photon. The proposed transmission scheme lays the groundwork for novel quantum communication protocols with higher transmission rates and refined control over scalable quantum technologies.

Analyzing Quantum Error Resilience for Quantum Communication in Guided and Unguided Media

AbstractThis research examines quantum key distribution and its applications in guided and unguided quantum communication. The importance of secure communication in the quantum era requires a thorough exploration of both guided and unguided quantum communication strategies. The research aims to address the challenges posed by guided channels, such as fiber optics, and unguided channels, such as free‐space quantum communication. This study addresses existing knowledge gaps in quantum error resilience management and signal processing techniques in unguided quantum communication. Advanced quantum gate analysis, environmental noise analysis, and quantum channel modeling techniques are employed. The research presents key findings on the impact of gate imperfections on quantum error resilience in guided media, the influence of noise‐induced errors in unguided media, and a unified metric for assessing various error sources in guided channels. Additionally, the study analyses stabilizer codes and surface codes for error mitigation through quantum error correction strategies. Simulation results provide a benchmark for theoretical predictions and guide the refinement of quantum communication protocols. In this context, machine learning‐based error prediction is introduced as a cutting‐edge approach to enhance the robustness of quantum communication systems.

Transport of non-classical light mediated by topological domain walls in a SSH photonic lattice

Advancements in photonics technologies have significantly enhanced their capability to facilitate experiments involving quantum light, even at room temperature. Nevertheless, fully integrating photonic chips that include quantum light sources, effective manipulation and transport of light minimizing losses, and appropriate detection systems remains an ongoing challenge. Topological photonic systems have emerged as promising platforms to protect quantum light properties during propagation, beyond merely preserving light intensity. In this work, we delve into the dynamics of non-classical light traversing a Su-Schrieffer-Heeger photonic lattice with topological domain walls. Our focus centers on how topology influences the quantum properties of light as it moves across the array. By precisely adjusting the spacing between waveguides, we achieve dynamic repositioning and interaction of domain walls, facilitating effective beam-splitting operations. Our findings demonstrate high-fidelity transport of non-classical light across the lattice, replicating known results that are now safeguarded by the topology of the system. This protection is especially beneficial for quantum communication protocols with continuous variable states. Our study enhances the understanding of light dynamics in topological photonic systems and paves the way for high-fidelity, topology-protected quantum communication.

Application of superthermal light to imaging and quantum communication protocols

The development of quantum technologies based on optical platforms demands an adequate engineering of the employed quantum states of light. In this framework, we show that superthermal states generated by sending a coherent beam through a sequence of two diffusers in cascade represent good candidates for different applications. Here, we summarize some recent results achieved exploiting this kind of light and show that it can be used to realize a differential ghost-imaging scheme and to encode information in an underwater communication protocol based on mesoscopic twin-beam states and photon-number-resolving detectors. The good quality of the experimental results suggests further investigations on the possible application of this kind of light to different contexts.

Engineering quantum dots for improved single photon emission statistics.

High fidelity single photon sources are required for the implementation of quantum information processing and communications protocols. Although colloidal quantum dots (CQDs) are single photon sources, their efficacy is limited by their tendency to show finite multiphoton emission at higher excitation powers. Here, we show that wave function engineering of CQDs enables the realization of emitters with significantly improved single photon emission performance. We study the ZnS/CdSe/CdS system. It is shown that this system offers significantly improved probabilities of single photon emission. While conventional CQDs such as CdSe/CdS exhibit a g2(0) > 0.5 ± 0.02 at ⟨N⟩ = 2.17, ZnS/CdSe/CdS show a greatly improved g2(0) ≈ 0.04 ± 0.01. Improved single photon emission performance encourages the use of colloidal materials as quantum light sources in emerging quantum devices.

Quantum networks using counterfactual quantum communication

Counterfactual quantum communication is one of the most interesting facets of quantum communication, allowing two parties to communicate without any transmission of quantum or classical particles between the parties involved in the communication process. This aspect of quantum communication originates from the interaction-free measurements where the chained quantum Zeno effect plays an important role. Here, we propose a new counterfactual quantum communication protocol for transmitting an entangled state from a pair of electrons to two independent photons. Interestingly, the protocol proposed here shows that the counterfactual method can be employed to transfer information from house qubits to flying qubits. Following this, we show that the protocol finds uses in building quantum repeaters leading to a counterfactual quantum network, enabling counterfactual communication over a linear quantum network.